diff --git a/src/agents/model-fallback.probe.test.ts b/src/agents/model-fallback.probe.test.ts
index ea843eb14889..3a1dfb1cc2e3 100644
--- a/src/agents/model-fallback.probe.test.ts
+++ b/src/agents/model-fallback.probe.test.ts
@@ -28,8 +28,42 @@ vi.mock("./provider-model-normalization.runtime.js", () => ({
 }));
 
 const emptyPluginMetadataSnapshot = vi.hoisted(() => ({
+  policyHash: "model-fallback-probe-test-empty-plugin-policy",
   configFingerprint: "model-fallback-probe-test-empty-plugin-metadata",
+  index: {
+    hostContractVersion: "test",
+    compatRegistryVersion: "test",
+    migrationVersion: 1,
+    policyHash: "model-fallback-probe-test-empty-plugin-policy",
+    generatedAtMs: 0,
+    installRecords: {},
+    plugins: [],
+    diagnostics: [],
+  },
+  registryDiagnostics: [],
+  manifestRegistry: { plugins: [], diagnostics: [] },
   plugins: [],
+  diagnostics: [],
+  byPluginId: new Map(),
+  normalizePluginId: (pluginId: string) => pluginId,
+  owners: {
+    channels: new Map(),
+    channelConfigs: new Map(),
+    providers: new Map(),
+    modelCatalogProviders: new Map(),
+    cliBackends: new Map(),
+    setupProviders: new Map(),
+    commandAliases: new Map(),
+    contracts: new Map(),
+  },
+  metrics: {
+    registrySnapshotMs: 0,
+    manifestRegistryMs: 0,
+    ownerMapsMs: 0,
+    totalMs: 0,
+    indexPluginCount: 0,
+    manifestPluginCount: 0,
+  },
 }));
 
 vi.mock("../plugins/current-plugin-metadata-snapshot.js", () => ({
diff --git a/src/agents/pi-embedded-runner-extraparams.test.ts b/src/agents/pi-embedded-runner-extraparams.test.ts
index 2da5c92a2e50..327f2807735c 100644
--- a/src/agents/pi-embedded-runner-extraparams.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams.test.ts
@@ -5,6 +5,7 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { testing as extraParamsTesting } from "./pi-embedded-runner/extra-params.js";
 
 vi.mock("../plugins/provider-hook-runtime.js", () => ({
+  clearProviderRuntimePluginCacheForTest: vi.fn(),
   testing: {
     buildHookProviderCacheKey: () => "test-provider-hook-cache-key",
   },
diff --git a/src/agents/pi-embedded-runner.sanitize-session-history.test-harness.ts b/src/agents/pi-embedded-runner.sanitize-session-history.test-harness.ts
index 62ec65356540..c611e9cda5c5 100644
--- a/src/agents/pi-embedded-runner.sanitize-session-history.test-harness.ts
+++ b/src/agents/pi-embedded-runner.sanitize-session-history.test-harness.ts
@@ -88,6 +88,7 @@ export function createSanitizeSessionHistoryProviderHookRuntimeMock(
   extra: Record<string, unknown> = {},
 ) {
   return {
+    clearProviderRuntimePluginCacheForTest: vi.fn(),
     resolveProviderRuntimePlugin: vi.fn(() => undefined),
     resolveProviderHookPlugin: vi.fn(() => undefined),
     resolveProviderPluginsForHooks: vi.fn(() => []),
diff --git a/src/agents/pi-embedded-runner.sanitize-session-history.test.ts b/src/agents/pi-embedded-runner.sanitize-session-history.test.ts
index 8c6cdef9ac7d..d46c85567b5a 100644
--- a/src/agents/pi-embedded-runner.sanitize-session-history.test.ts
+++ b/src/agents/pi-embedded-runner.sanitize-session-history.test.ts
@@ -29,6 +29,7 @@ vi.mock("./pi-embedded-helpers.js", async () => ({
 }));
 
 vi.mock("../plugins/provider-hook-runtime.js", async () => ({
+  clearProviderRuntimePluginCacheForTest: vi.fn(),
   testing: {},
   prepareProviderExtraParams: vi.fn(() => undefined),
   resolveProviderHookPlugin: vi.fn(() => undefined),
diff --git a/src/agents/subagent-registry-completion.ts b/src/agents/subagent-registry-completion.ts
index da3ad3999b93..ddfbbc770218 100644
--- a/src/agents/subagent-registry-completion.ts
+++ b/src/agents/subagent-registry-completion.ts
@@ -1,3 +1,4 @@
+import { createSubsystemLogger } from "../logging/subsystem.js";
 import { getGlobalHookRunner } from "../plugins/hook-runner-global.js";
 import type { SubagentRunOutcome } from "./subagent-announce-output.js";
 import {
@@ -10,6 +11,8 @@ import {
 } from "./subagent-lifecycle-events.js";
 import type { SubagentRunRecord } from "./subagent-registry.types.js";
 
+const log = createSubsystemLogger("agents/subagent-registry-completion");
+
 export function runOutcomesEqual(
   a: SubagentRunOutcome | undefined,
   b: SubagentRunOutcome | undefined,
@@ -113,7 +116,10 @@ export async function emitSubagentEndedHookOnce(params: {
     params.entry.endedHookEmittedAt = Date.now();
     params.persist();
     return true;
-  } catch {
+  } catch (err) {
+    log.warn(
+      `failed to emit subagent_ended hook for run ${runId}: ${err instanceof Error ? err.message : String(err)}`,
+    );
     return false;
   } finally {
     params.inFlightRunIds.delete(runId);
diff --git a/src/agents/subagent-registry.ts b/src/agents/subagent-registry.ts
index a1eb95323f1e..3a8b8fb3017a 100644
--- a/src/agents/subagent-registry.ts
+++ b/src/agents/subagent-registry.ts
@@ -646,8 +646,10 @@ function restoreSubagentRunsOnce() {
     // Cold-start restore path: queue the same recovery pass that restart
     // startup also uses so resumed children are handled through one seam.
     scheduleSubagentOrphanRecovery();
-  } catch {
-    // ignore restore failures
+  } catch (err) {
+    log.warn(
+      `failed to restore subagent runs from disk: ${err instanceof Error ? err.message : String(err)}`,
+    );
   }
 }